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    SubjectRe: [PATCH 5/9] clocksource: tegra: Enable ARM arch_timer with TSC
    > >>> +
    > >>> + /* CNTFRQ */
    > >>> + asm("mcr p15, 0, %0, c14, c0, 0\n" : : "r" (freq));
    > >>> + asm("mrc p15, 0, %0, c14, c0, 0\n" : "=r" (val));
    > >>> + BUG_ON(val != freq);
    > >>
    > >> This is scary. CNTFRQ is only writable from secure mode, and will
    > >> explode in any other situation.
    > >>
    > >> Also, writing to CNTFRQ doesn't change the timer frequency! This is just
    > >> a way for secure mode to tell the rest of the world the frequency the
    > >> timer is ticking at. Unless you've wired the input clock to be able to
    > >> change the frequency?
    > >
    > > ATM, our upstream kernel is expected in secure mode. This situation
    > > may be changed later, though....
    >
    > I appreciate this. But I expect this kernel to be also used on the
    > non-secure side if someone tried to run KVM with it. And this would go
    > bang right away.
    >

    But the guest wouldn't necessarily have this peripheral, or any other Tegra114
    peripheral for that matter?

    Cheers,

    Peter.


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